Ultrasonic irradiation in the synthesis of nanohydroxyapatite: a chemically friendly technique for improving hemocompatibility and antibiofilm applications

This study explores the synthesis of nanohydroxyapatite (nHA) using high-frequency ultrasonic irradiation (UI), a chemically friendly technique aligned with green chemistry principles. Synthesis was achieved by varying the UI time (15, 30, 45, and 60 minutes) and the reaction medium. Water-based mixtures were used: water/acetone (W/ACET), water/tetrahydrofuran (W/THF), and water/ethanol (W/ETOH). The resulting nHA was characterized structurally using FTIR, XRD, TGA, and SEM. These analyses revealed the formation of carbonated nHA similar to biological apatite, with distinct morphologies and particle sizes dependent on the solvent used. All synthesized materials exhibited high thermal stability and yields exceeding 80%. Hemocompatibility studies showed that nHA samples obtained in the W/THF mixture presented low hemotoxicity (1-2 % hemolysis), and did not affect platelet ADP aggregation processes. Microbiological assays showed a significant reduction in P. aeruginosa biomass production (p<0.05) after 24 hours, particularly for nHA synthesized with the W/ETOH mixture. There was also a less bacterial colonization, cellular aggregates or formation of specialized structures when was treated with this bioceramic, compared to the commercial hydroxyapatite, suggesting potential antibiofilm properties. This research presents an original and efficient method for producing nHA as a promising biomaterial for tissue engineering and bone replacement applications.